When the main gun of a tank is fired, the smoke, heat and debris exiting from the muzzle of the gun form a cloud that obscures the ability of the gunner to see the target. Depending on the surrounding climatic conditions, this obscuration can last for several seconds. In all cases, the time period during obscuration is long enough that the gunner will not be able to see the immediate impact of the round he has fired.
In training gunners, it is extremely costly to use live ammunition and because if this, a procedure known as "dry fire" is utilized wherein the gunner goes through all of the steps in firing without the expenditure of ammunition. This dry fire procedure is also used in training and testing where the target cannot be fired on for safety or economic reasons.